Sarin Gas Used in Syria Blocks Body’s ‘Off Switch’

iStockphoto/Thinkstock(NEW YORK) -- Sarin, a chemical weapon that U.S. officials say has been used by Syrian President Bashar al-Assad's regime in the country's ongoing civil war, blocks the "off switch" for muscles and glands, paralyzing and suffocating its victims by exhausting their bodies, experts say.

The clear, colorless liquid -- developed in Nazi Germany as a pesticide -- quickly evaporates into sarin gas, which, if inhaled or absorbed through the skin or eyes, can cause deadly symptoms in a matter of seconds.

"Without an 'off switch,' the glands and muscles are constantly being stimulated," the U.S. Centers for Disease Control and Prevention says on its website, describing how sarin leads to sustained activation of acetylcholine receptors on vital tissues throughout the body. "They may tire and no longer be able to sustain breathing function."

Despite its deadly potential, sarin is more likely to injure than kill. Of more than 900 people exposed to the gas during terrorist attacks in Tokyo and Matsumoto, Japan, in the 1990s, only 17 people died, according to a 1996 report. The gas was also used during the Gulf War of the 1980s.

"Mild or moderately exposed people usually recover completely," the CDC said, describing how certain drugs and hospital care can reverse the gas' effects if administered quickly. "Severely exposed people are not likely to survive."